1. Field of the Invention
The present invention relates to a water-based ink set for ink-jet recording, a water-based ink, and an ink-jet recording method.
2. Description of the Related Art
In general, it is demanded for the water-based ink set for ink-jet recording that the hue is satisfactory and the durability or stoutness is excellent against light, heat, and ozone. A water-based ink set, which includes a water-based ink based on the use of a specified dye, has been suggested as the water-based ink set for ink-jet recording in which the hue is satisfactory the durability or stoutness is excellent against light, heat, and ozone.
However, some types of the specified dye as described above tend to cause the change in the easiness of diffusion into a recording medium depending on the change of the environmental condition for the use, as compared with general dyes. For example, the humidity affects the easiness of diffusion of the specified dye into the recording medium. For this reason, for example, when a water-based magenta ink, which contains the specified dye, is mixed with a water-based yellow ink and a water-based cyan ink on the recording medium to perform the recording with the process black (also referred to as “tri-color black” or “composite black”), then the color tone of magenta is weakened in the process black due to the diffusion of the specified dye in a high humidity environment, and the achromatic color (for example, a color within a range of gradation from the black color (black) to the gray color (gray)) appears as if the achromatic color is greenish.
In view of the above, an object of the present teaching is to provide a water-based ink set for ink-jet recording which provides a satisfactory hue, which is excellent in the durability or stoutness against light, heat, and ozone, and which makes it possible to suppress the color change of the secondary color on a recording medium in a high humidity environment.
Further, it is known that the water-based ink for ink-jet recording causes a phenomenon called “migration” in which the colorant blurs to the circumferential edge of the recorded portion after the recording on a recording medium. The migration tends to occur especially in a high humidity environment. In the ink-jet recording, two or more types of water-based inks are used to form a recorded portion of a secondary color in some cases. However, the recorded portion of the secondary color sometimes undergoes the color change depending on the degree of migration (migration level) of the water-based ink in the high humidity environment.
In order to suppress the migration, for example, the following procedure has been performed. That is, the color change, which is caused by the migration, is made inconspicuous by making the selection so that the maximum difference among the mutual migration levels is decreased in a plurality of water-based inks.
However, in the case of the conventional ink-jet recording method, it is necessary to mutually select the water-based inks in which the migration levels are relatively close to one another. A problem arises such that the range of selection of the water-based ink is narrow.
In view of the above, another object of the present teaching is to provide an ink-jet recording method which makes it possible to suppress the color change of a recorded portion of a secondary color in a high humidity environment even in the case of a combination of water-based inks in which the difference in the migration level is relatively large therebetween.